Active Ingredients. - The purgative properties of buckthorn are probably due, for the most part, to an uncrystallizable bitter substance called Rhamnocathartine, the descriptions of which are still somewhat vague. It has been questioned whether this principle may not be identical with rhamnine, another ingredient of buckthorn berries; but the latter is almost or quite tasteless, and can be shown by the microscope to present a regular crystalline structure. Rhamnocathartine must not be confounded with cathartic acid, C180H96N3O82, the active principle of senna, and found also in the bark of the Rhamnus Frangula. Rhamnocathartine seems to be a sure purgative, in two or three grain doses, for children, but is exceedingly disagreeable to take, and is slow in action.

Physiological Action. - The juice of the berries causes great dryness of the mouth and throat, with intolerable thirst, nausea, in certain cases vomiting, griping pains that extend throughout the abdomen and violent purging, the character of the evacuations being watery.

1 Mitscherlich, Der Cacao und die Chocolade. 1859. Quoted in Husemann, Pflan-zenstoffe, p. 98.

Therapeutic Action. - The juice spoken of was at one time prescribed in dropsy, also in gout and rheumatism, but now is seldom employed except in domestic practice, which regards it as a laxative suitable especially to children, in the form of syrup.

Preparations and Dose. - Syrupus: (B. Ph.) dose, 1/2 to 1 oz.; for young children, 1/2 drachm to 2 drachms. (Little used in this country.)